Connectivity case study: When the unthinkable happens

Ensuring global network reliability means overcoming the unpredictable every single day. In an increasingly volatile world defined by rising threats, industry shifts and vastly interconnected systems, stability is part of Arelion’s DNA and always has been, even over 30 years of organic network growth. Our teams were put to the test last summer when a critical fiber connection between two major cities required immediate replacement.

This outage would have affected up to 15 terabits of live traffic across numerous services. Yet through expert planning, close collaboration and resilient engineering, our teams pulled off the seemingly impossible, completing a phased, live migration of all services without impacting a single customer.

Let’s take a behind-the-scenes look at how our experts protected the connectivity our wholesale, cloud and enterprise customers depend on to keep their operations online, no matter the circumstances.

A complex migration

The replacement involved a system with dense capacity that could not be migrated wave by wave, further complicated by four different ownership layers, from original cable owner to supplier, to secondary supplier, to us. To make matters even more critical, these services supported essential industries, including aerospace, automotive and digital media. Any prolonged outage could have caused significant economic and societal impacts.

Upon investigation, our engineers discovered that no additional C-band capacity was available, with 75% already occupied. The alternate path offered higher attenuation, limiting usable wavelength capacity. The project required migration across two data centers with complex multi-floor layouts and physical fiber patching challenges. In addition, customer-specific technology preferences, routing needs and maintenance window requirements had to be carefully coordinated.

Navigating volatility 

We began by working with our supplier to reallocate C-band spectrum, identifying an opportunity to free enough capacity by migrating 75% of active services temporarily from the C-band to the L-band. After securing the agreement, our engineers executed phased C-to-L migrations, freeing sufficient C-band to support the rerouted traffic.

From there, we mapped all 15 terabits, including protected and unprotected wave customers, IP transit and backbone traffic, onto the alternate route. We connected our transponders to the supplier’s line systems, continuously monitoring attenuation, optical performance and service thresholds. When performance exceeded acceptable levels, we swiftly reassigned affected customers.

Customer engagement played a central role from day one. Our teams provided tailored migration options based on service type, performance requirements and operational risk. Numerous teams, including Sales, Network Architecture, Plan and Build, Customer Support and Engineering, collaborated with customers, equipment suppliers and third-party cable owners to coordinate several 8-hour phased service windows aligned with each customer’s needs.

Every step, every service window and every wavelength was carefully documented to ensure business continuity.

Providing reliable connectivity

This strategy freed up significant C-band spectrum to maintain performance on the alternative path, ensuring reliable services for essential industries and preserving societally critical connectivity. The team worked relentlessly, day and night, while keeping our customers fully informed throughout the process. This project proved our ability to deliver emergency traffic rerouting with minimal service disruption, even under multi-layer supplier complexities.

Thanks to our experts’ tireless efforts, all of the traffic was successfully rerouted, and not a single customer experienced an outage. This extraordinary achievement demonstrates exceptional teamwork, technical expertise and a deep commitment to customer service.

The project exemplifies what we can accomplish under pressure when working toward our shared vision of stable, seamless global connectivity, even when the unthinkable happens.